Deep brain stimulation (DBS) and other related procedures involving the implantation of leads and catheters in the brain are increasingly used to treat such conditions as Parkinson's disease, dystonia, essential tremor, seizure disorders, obesity, depression, motor control disorders, and other debilitating diseases. During these procedures, a catheter, lead, or other medical device is strategically placed at a target site in the brain.
Microelectrode recording is generally performed with a microelectrode recording (MER) system. The MER system includes a small diameter electrode with a relatively small surface area optimal for recording single cell activity. The microelectrode may essentially be an insulated wire that has at least the distal portion uninsulated to receive electrical signals. The microelectrode functions as a probe to locate an optimal site in the brain for deep brain stimulation. Activity detected through the microelectrode is recorded by the MER system.
After an optimal site in the brain for deep brain stimulation has been identified by the microelectrode recording, a macroelectrode is typically used to test whether the applied stimulation has the intended therapeutic effect. Once macrostimulation confirms that stimulation at the optimal site provides the intended therapeutic effect, the macroelectrode is withdrawn from the brain and a DBS lead is permanently implanted at the optimal site in the brain for deep brain stimulation.
The DBS lead may then be connected to a stimulation device, such as an implantable pulse generator (IPG) or other type of stimulator. The stimulation device is configured to generate the electrical current that is applied to the stimulation site within the brain. However, the stimulation device is often located at a site that is relatively distant from the stimulation site. For example, the stimulation device may be mounted under the skin of the chest. Hence, in many applications, the DBS lead must exit the skull or cranium, make a right-angle bend at the outer surface of the cranium, and then be routed to the location of the stimulation device. The extra-cranial portion of the DBS lead and the tight right angle bend present severe stress exposure for the lead and may result in the breakage of the lead, and thus premature explantation of the lead.